Air spring



Patented Oct. 12, 1926.

UNITED STATES JOHN J. MOELBOY, OF NEW HAVEN, CONNECTICUT, A S SIGNOR TO THE WESTINGHOUSE AIR SPRING COMPANY, OENEW HAVEN, CONNECTICUT, A. CORPORATION 01 PENN SYLVANIA.

AIR sramo Application filed larch 27, 1528. Serial No. 628,087.

This invention relates to pneumatic cushion devices and methods of operating the same, useful in the arts generally, and parlaifiularly'in connection with vehicles and the One object ofthe present invention is to provide a device comprising essentially a cylinder with a closed top divided by "a pistonhaving a sliding fit therein; the s ace above the piston being the main cus ion chamber containing am usually under presclaims.

sure and a suitable quantity of oil to serve as an oil seal for preventing air leakage; and the space below the piston containing atmospheric air admitted thereinto through the leaky mechanical seal or acking between the piston rod and the ottom wall of the cylinder, the chamber thus provided at the lower end of the cylinder serving to gradually check the recoil or rebound of the piston. I

Another object is the provision in such a st-ructure'of means for collecting oil leaking past the seal and restoring it to the chamber above the seal at a propriate periods in the operation of the (iievice.

Another object is the provision of means in the collecting chamber for positively causing the return of the stored oil to the cushion chamber, said last named means be-.

ing brought into operation at appropriate times by and during the operation of the spring members, whereby the life of the spring is prolonged indefinitely.

Another object is the provision of means in said device for confining the atmospheric air to the lower chamber, thus preventing or restraining the passage thereof into the collecting chamber or the cushion chamber.-

Other objects and features of novelty are pointed out hereinafter and in the appended In the accompanying drawing '1 have shown by way of illustration a sectional elevation of one form'of pneumatic spring embodying my new method of and apparatus for operating such devices.

The device consists of a suitable length of tubing 3, to the upper end of which a dome shaped head 4 is threaded, and' to the lower end of which a" cup-shaped casting 5 is I threaded.

A. piston or plunger carrying two an- Duh-'0 P' P mk ngs .6 and 7 s is as,

ranged to slide-.wi tubing 3 and divides the interior of the air spring into a variable volume load support-ing cushion chamber 8 and a rebound or recoil check chamber 9.

A piston rod 10 carries the piston or plunger and projects through the bottom 11 of the air spring and is connected by nut 12 to the outer end of a leaf spring of a ve- 1 held in pace against a shoulder 15 thereon bya threaded nut 16. 1

These two nuts 13 and 14 form supports for the cup packings 6 and 7 and their outer.

peripheries are preferably finished so as to form bearing surfaces adapted to slide on the inner surfaces of cylinder 3. In the,

event it is desired to utilize a cup shaped packing 17 facing into the chamber 9 to insure that no air leaks I ast-the cup packing 6 from said chamber, t e outer periphery of the nut 13 will be cut away a suflicient dis) tance to permit the interposition of the cup shaped packing 17 between said nut, and the wal of cylinder 3. Packing 6, or packings 6 and 17, as the case may be, are held 1n place on nut 13 by means of an annular washer 18 and a tubular retainer 19 which is held in place by cylindrical nut 14. The free edge of each of the cup shaped packings 6 and 7 is pressed against the lnner wall of cylinder 3 by means of cone expanders 20, and helical springs 21. Cup shaped packing 7 is held in place on annular flange 22 of annular nut 14 by means of an annular washer 23 and nut or follower 24 which, in turn, is held in place by nut 25 and lock nut 26 at the top of piston rod 10. The nut or follower 24 is formed with a relatively long cylindrical bearing surface 27.

Piston rod 10 from a point midway be-' tween the cup ackings 6 and 7 is drilled to the top. thereo to form an air chamber 28 and a screw threaded cap'29 is provided at the top and hermetically closing oif the chamber 28 at this point. Oil ducts 30, 30, extend from the bottom of the chamber 28 and open into'the space between the said cup packings, 6 and '7. The retainer 19 is pro vided with a number of oil holes 31, 31, near its upper edge and the space between the cup packings 6 and 7 serves as an 011 retaining chamber for maintaining a constant oil seal for the free edge of cup packing 6. Oil ducts 32, 32, are provided in the bottom of nut 1 permitting ready passage of oil between the wall 3 and the space between the cup packings 6 and 7.

A flanged bushing 33 formed from suitable bearing metal is placed within the central opening of bottom member 11 and serves as a bearing for the piston rod 10. An annular buffer 34 formed of some suitable soft material loosely surrounds piston rod 10 and rests on the bottom of chamber 9. This buffer or washer 34 may be of a soft felt wick washer saturated with oil and serve to insure lubrication of the piston rod at this point and to absorb any oil that may leak down fromthe top and hold it for the lubrication of therod 10 in the bearing 33..

Normally, the cushion chamber 8 will be filled with oil to approximately the level shown in the drawings the oil filling the spaces between the cup packings 6 and 7.

The act of filling the chamber 8 withoil preparatory to putting the device into service traps and confines a quantity of air or other elastic fluid in the chamber 28 and I make use of this chambered air or other elastic fluid in the operation of the device to aid and assist in maintaining a liquid sea'l between the lower extremity of the piston and the rebound chamber 9 and to keep the oil circulating to the bearing surfaces through the space above the cup washer 6.

It will be understood that the device will be initially charged with the required amount of air under ressure through a check valve conventionally shown at 35 and the air pumped will flow into the cushion chamber 8 of the device and be confined there, as is now well understood in the art.

In the operation of the device, with the embodiment of the invention as shown in the drawing, if no oil is forced past the cup washer 7 ,there will be no change in the level of the oil in chamber 28 and consequently no increase in the degree of compression of the air therein. On the other hand, should oil leak past, or be forced past, the cup washer 7, it will raise the level of the liquid in the chamber 28 and consequently no increase in the degree of compression of the air therein. On the other hand, should oil leak past, or be forced past, the cup washer 7 it will raise the level of the liquid in the e amber 28 and increase the degree of compression of the air therein and successive leakages of this character will build up a pressure in the chamber 28 and consequently place all the oil above the chamber 28 equals or exceeds a minimum pressure in the cushion chamber 8, at which time the excess liquid will be transferred to a point above the cup washer 7. For example, with a pressure in the chamber 8 of, say, to. 90 pounds per square inch for normal standing load, the pressure under working conditions varies therein from 150 to 200 pounds per square inch on the up stroke of the piston to 30 to 35 pounds per square inch on the down stroke thereof. F rom'the foregoing, it will be seen that I make use of the pumping action of the air spring to force the oil escaping from the air chamber 8 into another chamber and gradually build up a pressure therein which will exceed a minimum pressure of said chamber 8 and also avail myself of the pumping action of the chamber 8 at the minimum operating pressures below that built up in the auxiliary chamber 28 to positively draw the excess of oil from the. said chamber 28 back into the chamber 8, at appropriate times during the operation of the device. v

Should the cup washer 7, for any reason, break down while the spring is in use, the air chamber 28 will then take the rapid variations of pressures more or less direct and serve to protect the cup washer 6 from the deleterious effects of such rapid pressure variations and the consequent pumping action exerted onthe chamber 28 by the pressure variations in *chamber 8 will continue to serve to circulate. the oil above cup washer 6, as the unimpaired portion of the cup washer 7 will continue to act as a seal between the chamber 8 and the space above the cup washer 6, to all bearing parts of 'the piston, and the device will continue to work efficiently.

The construction above described for returning the escaped oil to the cushion chamher 8 has marked advantages in view of the fact that it has no moving parts to get out of order and, further, the transfer of the oil is automatically accomplished only at those times when oil has accumulated.

Furthermore, it will be apparent that the oil betwen the lon bearing 27 and the wall 3 in cushion cham er 8 is under pressure at all times, and I have discovered that by the employment of this arrangement, the device operates more smoothly and is more steady than similar devices in which such 1 a bearing is absent.

I claim as my invention:

1. An elastic fluid spring comprising in combination, two chambers, a piston, one of said chambers being of varying volume as said piston reciprocates and the other of substantially constant volume, and means forming a liquid seal between said chamcup washer 6 under increased pressure until bers.

the pressure exertedby the air confined in 2. An elastic fluid spring comprising in combination, a cylinder, a piston in said 0 linder, a chamber for elastic fluid on one s1de of said piston, a chamber for elastic fluid carried by said piston, and meansforming a liquid seal between said chambers.

3. In a vehicle spring, a cylinder, a piston closing oil a portion of said cylinder for a cushion chamber, a packing for the joint between said piston and cylinder, .and a liquid collecting chamber having a trapped elastic fluid compartment on the low pres sure side of said packing for transferrin liquid to the opposite side of said packing.

4. In a vehicle spring, a cylinder, a piston dividing the cylinder into a cushion chamber on one side and a rebound check chamber on the other side, a packing for the joint between said 1piston and cylinderyand a liquid collecting c amber having a trapped elastic fluid compartment on the low pressure side of said packing. I

5. In a vehicle spring, a cylinder, a piston closing off a portion of said cylinder for a cushion chamber, successive packin s for the joint between said piston and cy inder, and a trapped elastic fluid compartment communicating with the space between said packings for transferring liquid to the cushion chamber.

6. In a vehicle spring, a cylinder, a piston closing off an air-tight cushion fchamber in said cylinder, successive packings for the joint between said piston-and said cylinder, and an oil receiving chamber, having a trapped elastic fluid compartment in .the space between said packings for'transferring liquid to the cushion chamber.

.7. In a vehicle spring, a cylinder, 8,. pis-' ton closin ofi an air-tight cushion chamber in said cy inder, and a trapped elastic fluid compartment in said piston for transferring 9. In a vehicle spring, a cylinder, a piston closing off an air-ti ht cushion chamher in said cylinder, an a trapped elastic ,s

fluid in a compartment of substantially constant volume in said piston for exerting pressure against liquid entering said compartment.

10. In a vehicle sprin a cylinder, a piston, closing off an air tig t cushion chamber in said cylinder, and a trapped elastic fluid cql lnpartment of substantially constant volu e in said piston and extending above the piston into said chamber. I

11. In a vehiclespring, a cylinder, a piston closing oil a portion of said cylinder for a cushion chamber, successive packings for the joint between the piston and cylinder, and a trapped elastic fluid compartm'ent communicating with the space between said packings and extending above said piston and into saidchamber. I

In. testimony whereof I hereto afiix my signature.

JOHN J. McELROY. 

